The present invention relates to a printed substrate able to hold electric parts, and more specifically, to a substrate having wiring patterns formed on both surfaces thereof.
According to the conventional art of this field, small electric parts are arrayed on a plane of a printed substrate which has wiring patterns on one surface only, making it difficult to obtain a sufficient reduction in size. Further, small electric parts must be temporarily secured to the printed substrate by using a bonding agent or the like so that they can be soldered in a subsequent soldering step by an automatic soldering apparatus. Therefore, time consuming and troublesome operations were required for applying the bonding agent.